水源型水库的氮形态分布特征与水体富营养化的关系

The Relationship between the Distribution of Nitrogen Forms and Eutrophication of Water Source Reservoirs

根据实测水质数据,对东莞市某备用水源水库的氮形态分布特征及其与叶绿素a及水体综合营养指数(TLT)的关系进行了分析,旨在为预防或减轻水体富营养化提供理论依据。结果表明:水源型水库易受到营养性污染,呈中度或低度富营养化状态;氮形态在水库进水区以氨氮和硝酸盐氮为主,且占比均在45%以上,出水区以硝酸盐氮为主,且占比在75%以上,从进水区到出水区氨氮占比下降80%以上,季节变化对氮形态空间分布有一定影响,但影响程度不大;氨氮与叶绿素a和TLI无明显的相关性,不对水体富营养化产生直接作用;硝酸盐氮与叶绿素a和TLI呈负相关,对水体富营养化有一定的抑制作用;亚硝酸盐氮和有机氮同叶绿素a以及TLI呈正相关,对水体富营养化有促进作用。降低排入水库的氨氮和有机氮含量是有效预防或减轻水体富营养化的主要途径。

Based on detected water quality data, the distribution characteristics of different form nitrogen and its relationships to chlorophyll a （Chl-a） and comprehensive nutrition status index of water body （TLI） in a reservoir as drinking water source in Dongguan were analyzed to pro- vide theoretical bases for prevention and reduction of the eutrophication. The results showed that reservoirs of this kind may easily be polluted nu- tritionally and present moderate or low level of eutrophication ,and the nitrogen form was given priority to ammonia nitrogen and nitrate nitrogen whose proportion was more than 45% respectively in the inflow area,but priority to nitrate nitrogen whose proportion was as high as 75% and above in the outflow area of the reservoir, also the proportion of ammonia nitrogen drops by 80% and above during the process from the inflow area to the outflow area, and moreover seasonal variation gives little impact to the spatial distribution of nitrogen forms. It has been found from the analyses that ammonia nitrogen has no obvious correlation with Chl-a and TLI and doesn＇t give direct contribution to the eutrophication, and nitrate nitrogen presents negative correlation with Chl-a and TLI and has a certain inhibitory effect to the eutrophication, but nitrite nitrogen and organic nitrogen positively relate with Chl-a and TLI so that it stimulates the eutrophication. To reduce the input amount of ammonia nitrogen and organic nitrogen into the reservoir was the main way to effectively prevent or mitigate eutrophication of water body in reservoirs.